There are many medications that are formulated to be inhaled, including medications for respiratory diseases and problems and medications that are more easily and rapidly absorbed through the respiratory tissues. Such medications are often formulated as “mists”, that is, aerosols of droplets suspended in air, but may also be in the form of fine, dry powders.
There are various forms of inhalers designed for the administration of such medications, but each offers a number of problems. For example, both wet and dry inhalers must incorporate features that provide safe, long term storage for the medications before they are used, typically by encapsulation of the medications in cartridges or capsules that are loaded into the devices when the medications are to be used. The encapsulated medications must then be “opened” safely and in a manner compatible with the dispensing of the medications, which requires that the medications continue to be retained within the capsule or container, but in such a way as to allow the medication to be dispensed to the patient.
The opening of a medication cartridge or capsule and the extraction of the medication may present particular problems, depending upon the type of medication and the type of cartridge or capsule. For example, cartridges or capsules containing wet medications commonly contain a pressurized propellant. The capsule seal must therefore safely and reliably retain the pressurized contents during storage, which in itself will typically make the seal more difficult to open, and further requires that the capsule seal and the opening mechanism be designed so as to retain the pressurized contents when the seal is breached during the opening process, which present additional difficulties.
Dry medications, however, present a different set of equally difficult requirements and dry powder inhalers of the prior art have employed a number of different types of medication containers, such as blister packs and reservoir storage mechanisms, all of which have been unsatisfactory in one aspect or another. More recent dry powder inhalers of the prior art have employed gelatin capsules, which share certain problems of the other prior art medication containers, such as a tendency for the medications to “clump” and thus be difficult to release from the container, and which present problems particular to gelatin capsules and similar medication containers. For example, one of the major problems of gelatin capsules has been the flaking or shearing of capsule particulate, that is, the production of particles or dust of the capsule material during puncture or destruction of the capsule to gain access to the medication therein. While the capsule material particulate is typically too large to be inhaled into the patient's lungs, the particulate often enters the patient's throat and causes at least some degree of discomfort. This problem is in some respects somewhat analogous to the problem of “coring” in hypodermic needles wherein a hypodermic needle may “core” out a cylinder or plug of tissue when inserted into the body of a patient, rather than opening a passage into the tissue, and wherein as a consequence the freed cored tissue may block the passage through the needle.
For these reasons, among others, inhalers tend to be relatively complex devices that are correspondingly often difficult to use and are generally relatively expensive to manufacture. These characteristics in turn largely limit the common use of medication inhalers to regions or countries of relatively high economic and educational levels where they will be administered and used by relatively highly qualified and trained medical personnel and by relatively highly educated patients able to afford and effectively use such devices. There is a significant need, however, for relatively inexpensive, easy to use medication inhalers in economically limited regions of the world and by people, including medical personnel, of relatively low educational levels, and preferably of a single use, throw away form having significantly reduced storage and use requirements.
The present invention addresses these and other problems of the prior art.